This invention relates to the polymerization of olefinic monomers and compositions for catalyzing the polymerization of such monomers.
A revolution in the polymers industry has occurred over the last decade in which Single Site Organometallic Catalysts have been developed that lead to rapid polymerization of ethylene, propylene and other nonpolar olefins. The resulting polymers and co-polymers have excellent and controllable tacticity and other properties, with microstructures often tunable by the ligands in the catalyst. One generation of catalysts involves early transition metal metallocenes (pioneered by Kaminsky, Ewen, Brintzinger, and Bercaw and developed by Dow, Exxon, and other companies), as disclosed in A. Andersen, et al., Angew. Chem., Int. Ed. Engl. 1976, 15, 630; J. Ewen, J. Am. Chem. Soc. 1984, 106, 6355; W. Kaminsky, et al., Angew. Chem., Int. Ed. Engl. 1985, 24, 507; J. Ewen, et al., J. Am. Chem. Soc. 1988, 110, 6255; E. Coughlin, et al., J. Am. Chem. Soc. 1992, 114, 7606; U.S. Pat. Nos. 5,015,749; 5,057,475; 4,544,762, 1985; 5,234,878, 1993; and U.S. Pat. No. 5,003,095, 1995. Another involves late transition metal di-imines or tri-imines (pioneered by Brookhart and Gibson and developed by Dupont), as disclosed in L. Johnson, et al., J. Am. Chem. Soc. 1995, 117, 6414; B. Small, et al., J. Am. Chem. Soc. 1998, 120, 4049; G. Britovsek, et al., Chem. Commun. 1998, 849; WO 96/23010; and WO 98/27124.
Despite the industrial success of these catalysts, however, there remain many important challenges in developing catalysts for important polymers. In particular, the current generations of catalysts are generally not effective with important polar monomers such as vinyl chloride, methyl acrylates, vinyl acetate, and acrylonitrile. Indeed, the activity of current catalysts to polymerize monomers containing polar functionalities has been limited to the polymerization of large monomers with the polar group far removed from the vinyl moiety. See, e.g. T. Chung, Macromolecules 1988, 21, 865; T. Chung, et al., Macromolecules 1993, 26, 3019; M. Kesti, et al., J. Am. Chem. Soc. 1992, 114, 9679; P. Aaltonen, et al., Macromolecules 1995, 28, 5353; M. Galimberti, et al., J. Mol. Catal. 1995, 101, 1; and S. Mecking, et al., J. Am. Chem. Soc. 1998, 120, 888. For other polar monomers, these catalysts are generally inactive or become poisoned in the presence of basic polar monomers.
Using the techniques described herein, the invention provides catalysts that overcome the problems associated with existing olefin polymerization catalysts and provide for the efficient catalysis of the polymerization of a variety of polar monomers.
In general, in one aspect, the invention provides catalyst compositions for use in an olefin polymerization process. The compositions include a late transition metal, and a ligand completed with the late transition metal. The late transition metal is selected from the (IUPAC convention) Group 7 (Mn column), Group 8 (Fe column), Group 9 (Co column), Group 10 (Ni column) and Group 11 (Cu column) transition metals. The ligand is characterized by the general formula: 
Each E is an electronegative atom capable of donating electrons to the late transition metal. Each Y is a linking group independently selected from xe2x80x94Oxe2x80x94, xe2x80x94NRxe2x80x94, xe2x80x94CR2xe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94PRxe2x80x94, xe2x80x94SiR2xe2x80x94, and xe2x80x94G(CR2)mxe2x80x94, where each R is a substituent independently selected from H, halide, alkyl, substituted alkyl, heteroalkyl, aryl, substituted aryl, and heteroaryl, and where one or more R substituents can be incorporated in a ring structure, G is selected from O, N, and CR2, and m is an integer greater than or equal to 1. Each A is a Lewis acid, Each X is an electron-withdrawing group independently selected from Cl, F, Br, I, CF3, C6F5, H, alkyl, C6H5, C6R5, and CR3, where each R is a substituent independently selected from H, halide, alkyl, substituted alkyl, heteroalkyl, aryl, substituted aryl, and heteroaryl, and where one or more R substituents can be incorporated in a ring structure. Each Z is a substituent independently selected from H, halide, alkyl, substituted alkyl, heteroalkyl, aryl, substituted aryl, and heteroaryl, where one or more of X, Y and/or Z can be incorporated in a ring structure. Therein the late transition metal is also complexed with one or more additional ligands that are capable of adding to an olefin in a polymerization process and/or that are capable of being displaced by the olefin.
Particular embodiments can include one or more of the following features. E can be independently N or P. Each A can be independently selected from Al, B, Ga, In, Tl, Sc, Y, La and Lu. The late transition metal can be nickel, palladium or platinum. The late transition metal can be nickel, palladium or platinum, A can be aluminum or scandium, Y can be xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, or xe2x80x94CH2xe2x80x94, X can be Cl, F, CF3 or H, and Z can be H.
In general, in another embodiment, the invention provides compounds characterized by the general formula: 
TM is a late transition metal selected from the Group 7-11 transition metals. Each E is an electronegative atom capable of donating electrons to the late transition metal. Each Y is a linking group independently selected from xe2x80x94Oxe2x80x94, xe2x80x94NRxe2x80x94, xe2x80x94CR2xe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94PRxe2x80x94, xe2x80x94SiR2xe2x80x94, and xe2x80x94G(CR2)mxe2x80x94, where each R is a substituent independently selected from H, halide, alkyl, substituted alkyl, heteroalkyl, aryl, substituted aryl, and heteroaryl, and where one or more R substituents can be incorporated in a ring structure, G is selected from O, N, and CR2, and m is an integer greater than or equal to 1. Each A is a Lewis acid. Each X is an electron-withdrawing group independently selected from Cl, F, Br, I, CF3, C6F5, H, alkyl, C6H5, C6R5, and CR3, where each R is a substituent independently selected from H, halide, alkyl, substituted alkyl, heteroalkyl, aryl, substituted aryl, and heteroaryl, and where one or more R substituents can be incorporated in a ring structure, Each Z is a substituent independently selected from H, halide, alkyl, substituted alkyl, heteroalkyl, aryl, substituted aryl, and heteroaryl, where one or more of X, Y and/or Z can be incorporated in a ring structure. M is a polymerizable olefinic monomer, and n is an integer greater than or equal to one, such that (M)n is polymer derived from one or more olefinic monomer subunits. Qxe2x88x92 is a weakly coordinating anion.
Particular embodiments can include one or more of the following features. E can be independently N or P. Each A can be independently Al, B, Ga, In, Tl, Sc, Y, La or Lu. The late transition metal can be nickel, palladium or platinum. The late transition metal can be nickel, palladium or platinum, A can be aluminum or scandium, Y can be xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, or xe2x80x94CH2xe2x80x94, X can be Cl, F, CF3 or H, and Z can be H. (M)n can be a polymer derived from at least one polar functionalized xcex1-olefin. The xcex1-olefin(s) can be selected from vinyl chloride, vinyl acetate, acrylonitrile, methyl acrylate, methyl methacrylate, methyl vinyl ketone, and chloroprene. (M)n can be a copolymer derived from the one polar functionalized xcex1-olefin(s) and at least one non-polar xcex1-olefin. The non-polar xcex1-olefin can be ethylene, propylene, butene, styrene, butadiene, or norbornene.
In general, in still another aspect, the invention provides methods for polymerizing polar olefinic monomers. The methods include contacting a catalyst composition or compound as described above with at least one polar olefinic monomer under polymerization conditions sufficient to polymerize the at least one polar olefinic monomer. Copolymers with additional polar olefinic monomers or non-polar monomers can also be produced.
In general, in a fourth aspect, the invention provides computer-implemented methods for identifying polymerization catalyst for a polar olefin. The methods include providing mechanism information for a catalytic polymerization reaction, providing a catalyst template, assigning values to each of a plurality of variables representing the components of the catalyst template, systematically varying the values to generate a catalyst candidate, using the mechanism information to calculate a potential energy surface for each of the catalyst candidates, and comparing the potential energy surfaces to identify a catalyst for the catalytic polymerization reaction.
The mechanism information includes electronic data representing intermediates and transition states of the catalytic polymerization reaction. The catalyst template includes electronic data representing a catalyst structure characterized by the general formula: 
The values include: a value for TM representing a late transition metal from the Group 7-11 transition metals; one or more values for E, each representing an electronegative atom capable of donating electrons to the late transition metal; one or more values for Y, each representing a linking group independently selected from xe2x80x94Oxe2x80x94, xe2x80x94NRxe2x80x94, xe2x80x94CR2xe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94PRxe2x80x94, xe2x80x94SiR2xe2x80x94, and xe2x80x94G(CR2)mxe2x80x94, wherein each R is a substituent independently selected from H, halide, alkyl, substituted alkyl, heteroalkyl, aryl, substituted aryl, and heteroaryl, and wherein one or more R substituents can be incorporated in a ring structure, G is selected from O, N, and CR2, and m is an integer greater than or equal to 1; one or more values for A, each representing a Lewis acid; one or more values for X, each representing an electron-withdrawing group independently selected from Cl, F, Br, I, CF3, C6F5, H, alkyl, C6H5, C6R5, and CR3, where each R is a substituent independently selected from H, halide, alkyl, substituted alkyl, heteroalkyl, aryl, substituted aryl, and heteroaryl, and where one or more R substituents can be incorporated in a ring structure; one or more values for Z, each representing a substituent independently selected from H, halide, alkyl, substituted alkyl, heteroalkyl, aryl, substituted aryl, and heteroaryl, where one or more of X, Y and/or Z can be incorporated in a ring structure; one or more values for L, representing a plurality of ligands, the plurality of ligands including one or more polarizable monomers, a polymer derived from one or more polarizable monomers, and one or more additional ligands satisfying additional coordination sites of TM or adjusting an oxidation state of TM; and a value for Qxe2x88x92, representing a weakly coordinating anion.
In particular embodiments, the method can further include varying a value representing a salvation energy of the candidate catalysts. Comparing the potential energy surfaces can include performing a screening test for each of a plurality of candidate catalysts, by comparing an energy difference between two or more intermediate structures on the potential energy surfaces for each of the plurality of candidate catalysts, and selecting one or more of the plurality of candidate catalysts for further analysis based on the results of the screening test.
Among the advantages of the invention are one or more of the following. The catalysts described herein can produce high molecular weight polymers from polar monomers. The catalysts described herein can produce copolymers with controllable sequences of polar and non-polar monomers. The catalysts described herein can provide control over the degree of tacticity during olefin polymerization, leading, for example, to purely isotactic or purely syndiotactic polymers. The catalysts described here can provide control over polymer microstructure induced by selective cross-linking. The optimization techniques described herein can provide for the efficient identification of catalysts providing one or more of these advantages tailored to a particular monomer system.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.